BioEd Online

The number of giant pandas in a crucial wildlife reserve in western China seems to have doubled since 1998, say researchers in China and Britain. The discovery raises hopes that this iconic species is on the road to recovery.

"There are many more pandas in the wild than we thought," says animal geneticist Michael Bruford of Cardiff University, UK, who led the team that carried out the census in Wanglang Nature Reserve.

A beloved symbol of the conservation movement, the giant panda (Ailuropoda melanoleuca) once called China and most of Southeast Asia home. But pressure from human development has meant that these much-loved bears are now only found in mountainous regions of China's west.

Tracking and counting the bears is difficult, as they are reclusive and live at a range of altitudes. Three previous surveys have been carried out in the 300-square-kilometre Wanglang reserve, as part of the Chinese government's efforts to quantify the entire panda population. In 1968, conservationists counted 196 pandas, whereas surveys in 1985 and 1998 yielded tallies of just 19 and 27, respectively.

Favourable faeces

Large-scale bamboo die-offs in the 1980s may have caused the panda population to plummet since the first national survey was carried out. However, other factors, such as their habit of wide roaming and the incomplete coverage of the park's previous surveys may also have contributed to the low count.

Giant pandas are traditionally surveyed by examining their faeces. These samples are easier to obtain than a real-life sighting, says Bruford, as pandas defecate as much as 40 times a day. Previous estimates of population size were obtained by studying the different bite sizes of bamboo segments in the excrement, giving a tally of how many bears are present. But these measurements cannot determine accurately the gender or age of the animal.

Bruford and colleagues used a new method. They extracted DNA from mucus in the faecal samples, and counted the number of unique sequences. As they report in the journal Current Biology¹, they identified 66 different bears, 35 males and 31 females.

Bear facts look hopeful

That's more than double the number of bears found in the 1998 survey, the researchers point out. Bruford's team also discovered no evidence of inbreeding in the population, giving hope that the group will continue to grow.

In total, Bruford estimates that there might be 3,000 giant pandas in the wild. According to the 1998 survey, the total number of bears in China was just 1,596. Bruford argues that his genetic method should now be applied to other parks to produce a more definitive census.

There are many reasons why pandas are starting to rebound, says Karen Baragona, a conservationist at the World Wildlife Fund in Washington, DC. These include an increase in the number of nature reserves, improved conservation management and recent foresting policies such as logging bans.

As to whether the panda is making a full comeback, conservationists are uncertain. "People always ask how many pandas is enough. It's hard to answer that question," says Baragona.

Bruford warns that although the numbers are encouraging, careful monitoring of the panda population is necessary because their habitat is still threatened. "We're not saying that the panda is out of the woods," he says.

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